The present invention relates to the technical field of driving circuits, and particularly to a liquid crystal display driving method and drive device.
An existing liquid crystal display usually uses an overvoltage driving (Over Driver, OD) technology to solve a blurring problem. Each steady state of a liquid crystal molecule corresponds to a predetermined voltage. When a voltage is applied to an electrode, the liquid crystal molecule does not rotate to a target state, but achieves the state after a predetermined response time. When the voltage is higher, the molecule rotates faster. In a traditional liquid crystal display, a driving voltage applied to the liquid crystal molecule is a corresponding voltage of the target state, because different gray levels have different corresponding voltages, the molecule needs to rotate over different angles, resulting in different response times for the molecule to shift between the different gray levels. In the liquid crystal display using the overvoltage driving technology, the applied driving voltage is a little higher than the corresponding voltage of the target state in the beginning, making the liquid crystal molecule rotate faster, and when the target state is achieved, the voltage falls back to the corresponding voltage of the target state to maintain the state, thus the response time is efficiently shortened, and the response times for the molecule to shift between different gray levels can be more even.
The aforementioned overvoltage driving technology increases the reaction speed of the liquid crystal molecule through applying an electrical field larger than the one corresponding to the original steady state, to make the liquid crystal molecule rotate to a predetermined angle in less time, which can reduce the response time of the liquid crystal molecule to 8 ms or less. For example: shifting the liquid crystal molecule from an initial gray level (such as level 0) to a target gray level (such as level 128), setting the level 0 driving voltage to be 0V, the level 128 driving voltage to be 3V, when an image of the liquid crystal display transfers from level 0 to level 128, if the driving voltage is set to transfer from 0V to 3V, the liquid crystal molecule usually does not rotate fast enough. The driving voltage is usually set to transfer from 0V to 4V to increase the speed (assuming that 4V is a driving voltage of level 150), then an overvoltage driving lookup table (LUT) is needed. Thus when the voltage transfers from level 0 to level 128, an overvoltage driving gray level value of level 150 can be obtained through the lookup table, then the level 150 takes the place of the original level 128 for performing the overvoltage driving operation.
To increase the response speed of the liquid crystal panel, the overvoltage driving technology is widely used. The principle is determining whether each pixel electrode needs to perform the overvoltage driving through comparing the image change of the current and the previous frames, according to a gray level difference value of the current and the previous frame images of each pixel electrode. Practically, determining the set of the gray level difference threshold value needed by activating the overvoltage driving is very important. If the gray level difference threshold value to activate the overvoltage driving is set to be too small, an irregular image would result from a fluctuation of the front-end data login resulting in the wrong activation of the overvoltage driving. If the gray level difference threshold value of activating the overvoltage driving is set to be too large, it would result in part of the pixel electrode which should perform the overvoltage driving not performing the overvoltage driving, thereby affecting the response time. The existing design acquires a balance point between the gray level difference threshold values, which can be too large or too small, according to the actual image performance of the pixel electrode. Such a balance point is very difficult to precisely determine when it needs to perform the overvoltage driving to the pixel electrode. This problem of the existing technology badly needs to be improved.